Did you know that you can purify water by putting it in a bottle and letting it sit out in the sun for a few days? Me either. This method is called SODIS.
Katja Grace mentions that in a posting, which appears to have been triggered by an essay by Ker Than at the National Geographic. Who in turn was responding to prerelease PR for an article in PLoS Medicine.
A lot of misery and death comes of infectious agents picked up from the lousy water supply most humans draw upon. So this looks great. A low cost treatment for a widespread and aweful problem. All that’s left is to solve the coordination problem, e.g. getting the word out and changing behaviors.
That puts the problem into the same class as seat belts, moderate exercise, getting a will, buying life insurance, setting aside a few weeks of emergency supplies. Which is to say: it is a very hard social engineering problem.
The article is not about the hard social engineering, it skips over that. The article reports on a clinical trail intended to capture the Holy Grail of medical research: evidence of efficacy of the treatment. Sadly the study did not capture a statistically significant improvement in the incidence of child diarrhea between the villages where they applied intervened and those in the control group.
The article concludes: “Despite an extensive SODIS promotion campaign we found only moderate compliance with the intervention and no strong evidence for a substantive reduction in diarrhoea among children.” Unsurprisingly the authors are fans of evidence based medicine and so they goto write: “better evidence of how the well-established laboratory efficacy of this home-based water treatment method translates into field effectiveness under various cultural settings and intervention intensities.” Which is fine but kind of misses the point. That demands a end point, i.e. evidence of effective interventions, but first and foremost what’s required is that experts in effective social engineering be brought to the table.
It is hard to convince people to adopt new behaviors, particularly those that require immediate contributions and who’s benefit is statistical and distant. It has taken for ever to get people to wear seat belts, or adopt baby car seats, etc. etc. I am reminded of something I read years ago about how slowly the plow spread across the planet. I’m reminded of the experiment contrasting two campaigns to encourage testing for STD, where no significant difference was found between using fear v.s. rational arguments; but what did work was clearly telling people were the clinic was located. I’m reminded of how hard it is to get a work group to actually utilize a new productivity tool (a wiki, a group email list, a bug tracking system). This stuff is hard.
The vocabulary of health practitioners isn’t much help. Compliance? Intervention intensities?
Insta-theories about why the villagers didn’t adopt this technique are fun, just as long as you don’t get too wedded to any given insta-theory. What caught my attention in reading the Katja’s posting was how it had one insta-theory, which appears to have been gin’d up by one of the twelve authors when on the phone with Ker Than. It’s a fine insta-theory; but I had no trouble coming up with a dozen more. Their insta-theory was that the practice of setting you water out in the sun isn’t fashionable and so the villagers where embarrassed to seen doing it (in econo-legitmacy-speak we say “signalling”). Noting that during the study the researchers lost track of more that 10% of the households due to political unrest … well … I smell projection in that insta-theory.
Like I said this stuff is hard. People always try to skip the hard social engineering step; and then they make up insta-theories for why it didn’t work out.